1. Field of the Invention
This invention relates to thermal imaging devices. In particular the invention relates to thermal imaging devices incorporating as their thermo-optic conversion elements liquid crystals whose optical properties vary in dependence on the intensity of thermal radiation incident on the crystal so as to provide optical indications of the intensity of the incident thermal radiation.
2. Description of Related Art
Such an imaging device is described for example in Sov. J. Opt. Technol. 48 (2), 1981, pages 65-68. The device described in this publication incorporates a cholesteric liquid crystal which shows enhanced temperatures near a cholesteric-smectic phase transition. Several workers have subsequently made thermal imaging devices incorporating such crystals.